Independent manifold dual gas turbine fuel system

ABSTRACT

The present application provides a dual gas fuel delivery system and a method of delivering two gas fuels. The system may include (a) a low energy gas delivery system comprising a low energy gas inlet, a gas split, a low energy gas primary manifold outlet, and a low energy gas secondary manifold outlet; (b) a high energy gas delivery system comprising a high energy gas inlet and a high energy gas primary manifold outlet; (c) a primary manifold; and (d) a secondary manifold, wherein the low energy gas primary manifold outlet and the high energy gas primary manifold outlet are coupled to the primary manifold, wherein the low energy gas secondary manifold outlet is coupled to the secondary manifold, and wherein the low energy gas delivery system further comprises a primary low energy gas stop and pressure control valve between the gas split and the low energy gas primary manifold outlet.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application relates to U.S. patent application Ser. No.12/114,893 entitled “Single Manifold Dual Gas Turbine Fuel System;” U.S.patent application Ser. No. 12/114,905 entitled “Primary Manifold DualGas Fuel System;” and U.S. patent application Ser. No. 12/114,911entitled “Operation of Dual Gas turbine Fuel System.” These applicationsare incorporated herein by reference.

TECHNICAL FIELD

The present application relates to gas turbine fuel systems and moreparticularly relates to gas turbine fuel systems capable of deliveringtwo or more gaseous fuels to a single manifold.

BACKGROUND OF THE INVENTION

Modern gas turbines require precise control of the fuel system. Forexample, a pressure drop across the fuel nozzles must be carefullymaintained within a specified range in order to avoid combustor damage.In general, it may be difficult to operate a modern gas turbine on botha normal, high energy fuel (for example, natural gas) and a highhydrogen, low energy fuel (for example, syngas). What is desired,therefore, is a “dual gas” turbine fuel system that may both accommodateand control delivery of a high energy fuel, a low energy fuel, and a mixof high and low energy fuels.

The design of such a “dual gas” fuel system may be complicated by thedifferent characteristics of the fuels. Operating a gas turbine with alow energy fuel requires a significantly higher volumetric flow ratethan does operating a gas turbine with a high energy fuel. Furthermore,a low energy fuel, which is typically derived from a gasificationprocess, often may be supplied at a temperature up to or exceeding 500°F. (about 260 degrees Celsius). These characteristics necessitate fuelsystem hardware that can accommodate and control large variations inboth fuel temperature and volumetric flow rate. Unfortunately, thishardware may be large, complicated, and expensive. What is desired,therefore, is a “dual gas” turbine system that uses smaller, standard,simplified hardware so as to save hardware costs, maintenance costs, andfloor space.

BRIEF DESCRIPTION OF THE INVENTION

The present application thus provides a dual gas fuel delivery systemand a method of delivering two gas fuels.

The dual gas fuel delivery system may include (a) a low energy gasdelivery system comprising a low energy gas inlet, a gas split, a lowenergy gas primary manifold outlet, and a low energy gas secondarymanifold outlet; (b) a high energy gas delivery system comprising a highenergy gas inlet and a high energy gas primary manifold outlet; (c) aprimary manifold; and (d) a secondary manifold, wherein the low energygas primary manifold outlet and the high energy gas primary manifoldoutlet are coupled to the primary manifold, wherein the low energy gassecondary manifold outlet is coupled to the secondary manifold, andwherein the low energy gas delivery system further comprises a primarylow energy gas stop and pressure control valve between the gas split andthe low energy gas primary manifold outlet.

The method of delivering fuel to a turbine may include (a) feeding a lowenergy gas to a low energy gas inlet of a low energy gas deliverysystem; (b) feeding a high energy gas to a high energy gas inlet of ahigh energy gas delivery system; (c) passing a first portion of the lowenergy gas through a primary low energy gas stop and pressure controlvalve; (d) feeding the first portion of the low energy gas to a primarymanifold from a low energy gas primary manifold outlet of the low energygas delivery system; (e) feeding a second portion of the low energy gasto a secondary manifold from a low energy gas secondary manifold outletof the low energy gas delivery system; (t) feeding the high energy gasto the primary manifold from a high energy gas primary manifold outletof the high energy gas delivery system; (g) feeding the high energy gasand the first portion of the low energy gas to a turbine from theprimary manifold; and (h) feeding the second portion of the low energygas to the turbine from the secondary manifold.

These and other features of the present application will become apparentto one of ordinary skill in the art upon review of the followingdetailed description when taken in conjunction with the drawings and theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram that depicts an independent manifold dual gasfuel system.

DETAILED DESCRIPTION OF THE INVENTION

The present application provides a dual gas fuel delivery system and amethod of delivering a number of gas fuels.

I. Independent Manifold Dual Gas Fuel Delivery System

Referring now to the drawings, FIG. 1 shows a configuration of anindependent manifold dual gas fuel delivery system 100. The system 100may be used to deliver a high energy gas, a low energy gas, or a mixtureof the high energy gas and the low energy gas to a turbine. Importantly,the system 100 may deliver both high energy fuel and low energy fuelwhile only allowing the high energy fuel to enter a single manifold. Bydelivering the high energy fuel to only a single manifold, the system100 may reduce the amount of energy stored in the manifolds and therebyreduce the risk of turbine over-speed.

The Gas Fuels

They system 100 may deliver a high energy gas, a low energy gas, or amixture of high energy gas and low energy gas. The high energy gas mayhave an energy value in a range from about 900 to about 1100 BTU/ft³.The low energy gas may have an energy value in a range from about 125 toabout 350 BTU/ft³. In a particular embodiment, the difference in energyvalues between the high energy gas and the low energy gas is in a rangefrom about 550 to about 975 BTU/ft³.

The Delivery System

The independent manifold dual gas fuel delivery system 100 may include alow energy gas delivery system 102, a high energy gas delivery system104, a primary manifold 106, and a secondary manifold 108. The secondarymanifold 108 may have a size that is larger than the size of the primarymanifold 106. For example, the secondary manifold 108 may have a largervolume and/or fuel nozzle area as compared to the primary manifold 106.The application of both the primary manifold 106 and the secondarymanifold 108 may allow the turbine to operate at a wide range of loadsusing either the low energy gas, the high energy gas, or a mixture ofthe high energy gas and the low energy gas.

The low energy gas delivery system 102 may include a low energy gasinlet 110, a gas split 112, a low energy gas primary manifold outlet114, and a low energy gas secondary manifold outlet 116. The high energygas delivery system 104 may include a high energy gas inlet 118 and ahigh energy gas primary manifold outlet 120. The primary manifold 106may include a primary manifold piping inlet 122 and a primary manifoldnozzle outlet 124. The secondary manifold 108 may include a secondarymanifold piping inlet 126 and a secondary manifold nozzle outlet 128.The low energy gas primary manifold outlet 114 and the high energy gasprimary manifold outlet 120 may be coupled to the primary manifold 106.For example, the low energy gas primary manifold outlet 114 and the highenergy gas primary manifold outlet 120 may merge into the primarymanifold piping inlet 122. The low energy gas secondary manifold outlet116 may be coupled to the secondary manifold 108. For example, the lowenergy gas secondary manifold outlet 116 may merge into the secondarymanifold piping inlet 126.

The low energy gas delivery system 102 also may include primary lowenergy gas control valve 130 between the gas split 112 and the lowenergy gas primary manifold outlet 114. Likewise, the high energy gasdelivery system 104 also may include a high energy gas control valve 132between the high energy gas inlet 118 and the high energy gas primarymanifold outlet 120. The gas control valves 130 and 132 may control theflow of fuel to the primary manifold 106 so that a precise pressure dropis maintained across the primary manifold nozzle 124.

The low energy gas delivery system 102 also may include a secondary lowenergy gas control valve 134. The secondary low energy gas control valve134 may be located between the gas split 112 and a low energy gassecondary manifold outlet 116. The secondary low energy gas controlvalve 134 may control the flow of fuel in the secondary manifold 108 sothat a precise pressure drop is maintained across the secondary manifoldnozzle outlet 128. The secondary low energy gas control valve 134 alsomay be used to stop the flow of gas through the secondary manifold 108.

The low energy gas delivery system 102 also may include any number ofadditional gas control valves. For example, the low energy gas deliverysystem 102 also may include a second secondary low energy gas controlvalve 136 and a third secondary low energy gas control valve 138. Thecontrol valves 136 and 138 may be located between the gas split 112 anda low energy gas secondary manifold outlet 116. The three control valves134, 136 and 138 may operate in parallel. The use of multiple gascontrol valves may allow each control valve to be of a smaller size,which may in turn allow for the use of off the shelf gas control valves.

The low energy gas delivery system 102 also may include a primary lowenergy gas stop and pressure control valve 140 between the gas split 112and the primary low energy gas control valve 130. Likewise, the highenergy gas delivery system 104 also may include a high energy gas stopand pressure control valve 142 between the high energy gas inlet 118 andthe high energy gas control valve 132. The stop and pressure controlvalves 140 and 142 may control the flow of fuel upstream of the gascontrol valves 130 and 132 so that a constant reference pressure ismaintained between the stop and pressure control valves 140 and 142 andthe gas control valves 130 and 132. By maintaining the areas of constantreference pressure immediately upstream of the gas control valves 130and 132, the rate of flow through the gas control valves may becalculated using the only the positions (effective areas) of the controlvalves.

The low energy gas delivery system 102 also may include a secondary lowenergy gas stop and pressure control valve 144 between the gas split 112and the secondary low energy gas control valve 134. The stop andpressure control valve 144 may control the flow of fuel upstream of thegas control valve 134 so that a constant reference pressure ismaintained between the stop and pressure control valves 144 and the gascontrol valve 134. By maintaining the area of constant referencepressure immediately upstream of the gas control valve 134, the rate offlow through the gas control valve may be calculated using the only theposition (effective area) of the control valve.

The low energy gas delivery system 102 also may include a low energy gasstop valve 146 between the low energy gas inlet 110 and the gas split112. Likewise, the high energy gas delivery system 104 also may includehigh energy gas stop valve 148 between the high energy gas inlet 118 andthe high energy gas stop and pressure control valve 142. The stop valves146 and 148 may be used to stop the flow of gas through the low energygas delivery system 102 and the high energy gas delivery system 104,respectively. For example, if the turbine is operating on high energygas only, the low energy gas stop valve 146 may stop the flow of gasthrough the low energy gas delivery system 102 so that only high energyfuel will flow through the primary manifold 106. Furthermore, if theturbine is operating on low energy gas only, the high energy gas stopvalve 148 may stop the flow of gas through the high energy gas deliverysystem 104 so that only low energy fuel will flow through the primarymanifold 106.

The low energy gas delivery system 102 also may include a primary lowenergy gas purge system between the low energy gas inlet 110 and theprimary low energy gas control valve 130. The primary low energy gaspurge system may include a primary low energy gas purge inlet 150, afirst primary low energy gas purge vent 152, and a second primary lowenergy gas vent 154. The primary low energy gas purge inlet 150 may belocated between the primary low energy gas control valve 130 and theprimary low energy gas stop and pressure control valve 140, the firstprimary low energy gas purge vent 152 may be located between the primarylow energy gas control valve 130 and the primary low energy gas stop andpressure control valve 140, and the second primary low energy gas vent154 may be located between the primary low energy gas stop and pressurecontrol valve 140 and the low energy gas stop valve 146. The primary lowenergy gas purge system may be used to reduce the risk of combustionwhen the low energy gas delivery system 102 is not in use.

The high energy gas delivery system 104 also may include a high energygas purge system between the high energy gas inlet 118 and the highenergy gas outlet 120. The high energy gas purge system may include ahigh energy gas purge inlet 156, a first high energy gas vent 158, and asecond high energy vent 160. The high energy gas purge inlet 156 may belocated between either (a) the high energy gas control valve 132 and theprimary manifold nozzle outlet 124 or (b) the low energy gas controlvalve 130 and the primary manifold nozzle outlet 124, the first highenergy gas vent 158 may be located between the high energy gas controlvalve 132 and the high energy gas stop and pressure control valve 142,and the second high energy gas vent 160 may be located between the highenergy gas stop and pressure control valve 142 and the high energy gasstop valve 148. The gas purge system may be used to reduce the risk ofcombustion during trip of the turbine while running a mix of high andlow energy gas or low energy gas only in both manifolds.

The low energy gas delivery system 102 also may include a secondary lowenergy gas purge system between the gas split 112 and the secondary lowenergy gas control valve 134. The secondary low energy gas purge systemmay include a first secondary low energy gas purge inlet 162, a secondsecondary low energy gas purge inlet 164, and a secondary low energy gaspurge vent 166. The first secondary low energy gas purge inlet 162 andthe secondary low energy gas purge vent 166 may be located between thesecondary low energy gas stop and pressure control valve 144 and thesecondary low energy gas control valve 134, and the second secondary lowenergy gas purge inlet 164 may be located between the secondary lowenergy gas control valve 134 and the secondary manifold nozzle outlet128. The secondary manifold purge system may be used to reduce the riskof combustion when the secondary manifold 108 is not in use. Forexample, the first secondary low energy gas purge inlet 162 and thesecondary low energy gas purge vent 166 may create an inert gas pressurebuffer between the secondary low energy gas stop and pressure controlvalve 144 and the secondary low energy gas control valve 134 in orderisolate the low energy fuel from the CPD purge air.

The low energy gas delivery system 102 also may include a low energy gasstrainer 168 between the low energy gas inlet 110 and the low energy gasstop valve 146. Likewise, the high energy gas delivery system 104 alsomay include a high energy gas strainer 170 between the high energy gasinlet 118 and the high energy gas stop valve 148. The strainers 168 and170 may filter debris out of the fuel in order to prevent problems suchas clogging in the independent manifold dual gas fuel delivery system100.

The low energy gas delivery system 102 also may contain a low energy gasbypass outlet 172 between the low energy gas inlet 110 and the lowenergy gas stop valve 146. Likewise, the high energy gas delivery system104 also may include a high energy gas bypass outlet 174 between thehigh energy gas inlet 118 and the high energy has stop valve 148. Thebypass outlets 172 and 174 may feed gas to systems such as a vent orflare for condensation risk mitigation.

The independent manifold dual gas fuel delivery system 100 also mayinclude a compressor discharge pressure system 176 (“CPD system”). TheCPD system 176 may include a CPD air inlet 178 and a CPD air outlet 180.The CPD system 176 may be coupled to the secondary manifold 108. Forexample, CPD air outlet 180 may merge into the secondary manifold pipinginlet 126. The CPD system 176 may be used to purge the secondarymanifold 108 of gas, maintain a positive nozzle pressure ratio in thesecondary manifold 108, and/or keep the secondary manifold nozzle outlet128 cool.

The CPD system 176 may include a primary CPD valve 182 between the CPDair inlet 178 and the CPD air outlet 180. The CPD system 176 also mayinclude a secondary CPD valve 184 between the CPD air inlet 178 and theprimary CPD valve 182. The CPD valves 182 and 184 may control the flowof air to the secondary manifold 108 so that a precise pressure drop ismaintained across the secondary manifold nozzle outlet 128.

The CPD system 176 also may include a CPD gas purge inlet 186 and a CPDgas purge vent 188. The CPD gas purge inlet 186 and the CPD gas purgevent 188 may be located between the secondary CPD valve 184 and theprimary CPD valve 182. The CPD gas purge inlet 186 and the CPD gas purgevent 188 may be used to reduce the risk of combustion when the CPDsystem 176 is not in use. For example, the CPD gas purge inlet 186 andthe CPD gas purge vent 188 may create an inert gas pressure bufferbetween the secondary CPD valve 184 and the primary CPD valve 182 inorder isolate the low energy gas from the CPD air.

The independent manifold dual gas fuel delivery system 100 may be usedto deliver two gas fuels to a turbine. A low energy gas may be fed tothe low gas energy inlet 110 of the low energy gas delivery system 102.A first portion of the low energy gas then may be fed to the primarymanifold piping inlet 122 of the primary manifold 106 from the lowenergy gas primary manifold outlet 114 of the low energy gas deliverysystem 102, and a second portion of the low energy gas may be fed to thesecondary manifold piping inlet 126 of the secondary manifold 108 fromthe low energy gas secondary manifold outlet 116 of the low energy gasdelivery system 102. Furthermore, the first portion of the low energygas may be passed through the primary low energy gas stop and pressurecontrol valve 140 after the step of feeding the low energy gas to thelow energy gas delivery system 102 and before the step of feeding thefirst portion of the low energy gas to the primary manifold 106. A highenergy gas may be fed to the high energy gas inlet 118 of the highenergy gas delivery system 104. The high energy gas then may be fed tothe primary manifold piping inlet 122 of the primary manifold 106 fromthe high energy gas primary manifold outlet 120 of the high energy gasdelivery system 104.

The high energy gas and the first portion of the low energy gas may befed to the turbine from the primary manifold nozzle outlet 124 of theprimary manifold 106. The second portion of the low energy gas may befed to the turbine from the secondary manifold piping outlet 128 of thesecondary manifold 108.

The method of delivering the two gas fuels to the turbine may include astep of passing the first portion of the low energy gas through theprimary low energy gas control valve 130 after the step of passing thefirst portion of the low energy gas through the primary low energy gasstop and pressure control valve 140 and before the step of feeding thefirst portion of the low energy gas to the primary manifold 106. Themethod also may include a step of passing the second portion of the lowenergy gas through the secondary low energy gas control valve 134 afterthe step of feeding the low energy gas to the low energy gas deliverysystem 102 and before the step of feeding the second portion of the lowenergy gas to secondary manifold 108. Furthermore, the method mayinclude a step of passing the second portion of the low energy gasthrough the secondary low energy gas stop and pressure control valve 144after the step of feeding the low energy gas to the low energy gasdelivery system 102 and before the step of feeding the second portion ofthe low energy gas through the secondary low energy gas control valve134. Finally, the method of delivering the two gas fuels to the turbinemay include passing the low energy gas through the low energy gas stopvalve 146 after the step of feeding the low energy gas to the low energygas delivery system 102 and before the steps of passing the firstportion of the low energy gas through the primary low energy gas stopand pressure control valve 140 and passing the second portion of the lowenergy gas through the secondary low energy gas stop and pressurecontrol valve 144.

The method of delivering the two gas fuels to the turbine may include astep of passing the high energy gas through the high energy gas controlvalve 132 after the step of feeding the high energy gas to the highenergy gas delivery system 104 and before the step of feeding the highenergy gas to the primary manifold 106. The method also may include astep of passing the high energy gas through the high energy gas stop andpressure control valve 142 after the step of feeding the high energy gasto the high energy gas delivery system 104 and before the step ofpassing the high energy gas through the high energy gas control valve132. Finally, the method of delivering the two gas fuels to the turbinemay include passing the high energy gas through the high energy gas stopvalve 148 after the step of feeding the high energy gas to the highenergy gas delivery system 104 and before the step of passing the highenergy gas through the high energy gas stop and pressure control valve142.

It should be understood that the foregoing relates only to the preferredembodiments of the present application and that numerous changes andmodifications may be made herein without departing from the generalspirit and scope of the invention as defined by the following claims andthe equivalents thereof.

1. A fuel delivery system, comprising: a turbine operable at a range ofloads from a start-up load to a full load; a primary manifold forsupplying a fuel composition to the turbine, the fuel compositioncomprising a low energy gas, a high energy gas, or a blend of the lowenergy gas and the high energy gas; a secondary manifold for supplyingthe low energy gas to the turbine; a low energy gas delivery systemcomprising a low energy gas inlet, a gas split for feeding a firstportion of the low energy gas to the primary manifold and feeding asecond portion of the low energy gas to the secondary manifold, a lowenergy gas primary manifold outlet coupled to the primary manifold, alow energy gas secondary manifold outlet coupled to the secondarymanifold, and a primary low energy gas stop and pressure control valvebetween the gas split and the low energy gas primary manifold outlet;and a high energy gas delivery system comprising a high energy gas inletand a high energy gas primary manifold outlet coupled to the primarymanifold, wherein the fuel delivery system is configured to allow thehigh energy gas to be delivered only to the primary manifold low energygas.
 2. The system of claim 1, wherein: the low energy gas deliverysystem further comprises a primary low energy gas control valve betweenthe primary low energy gas stop and pressure control valve and the lowenergy gas primary manifold outlet; the low energy gas delivery systemfurther comprises a secondary low energy gas control valve between thegas split and the low energy gas secondary manifold outlet; and the highenergy gas delivery system further comprises a high energy gas controlvalve between the high energy gas inlet and the high energy gas primarymanifold outlet.
 3. The system of claim 2, wherein: the low energy gasdelivery system further comprises a secondary low energy gas stop andpressure control valve between the gas split and the secondary lowenergy gas control valve; and the high energy gas delivery systemfurther comprises a high energy gas stop and pressure control valvebetween the high energy gas inlet and the high energy gas control valve.4. The system of claim 3, wherein: the low energy gas delivery systemfurther comprises a low energy gas stop valve between the low energy gasinlet and the gas split; and the high energy gas delivery system furthercomprises a high energy gas stop valve between the high energy gas inletand the high energy stop and pressure control valve.
 5. The system ofclaim 2, wherein: the low energy gas delivery system further comprises aprimary low energy gas purge system between the low energy gas inlet andthe primary low energy gas control valve; the low energy gas deliverysystem further comprises a secondary low energy gas purge system betweenthe gas split and the secondary low energy gas control valve; and thehigh energy gas delivery system further comprises a high energy gaspurge system between the high energy gas inlet and the high energy gasprimary manifold outlet.
 6. The system of claim 1, further comprising: acompressor discharge pressure system comprising a compressor dischargepressure inlet and a compressor discharge pressure outlet, wherein thecompressor discharge pressure outlet is coupled to the secondarymanifold.
 7. The system of claim 6, wherein: the compressor dischargepressure system further comprises a compressor discharge pressure valvebetween the compressor discharge pressure inlet and the compressordischarge pressure outlet.
 8. A method of delivering a fuel compositionto a turbine, comprising: providing a fuel delivery system, the fueldelivery system comprising: a turbine operable at a range of loads froma start-up load to a full load; a primary manifold for supplying a fuelcomposition to the turbine, the fuel composition comprising a low energygas, a high energy gas, or a blend of the low energy gas and the highenergy gas; a secondary manifold for supplying the low energy gas to theturbine; a low energy gas delivery system comprising a low energy gasinlet, a gas split for feeding a first portion of the low energy gas tothe primary manifold and feeding a second portion of the low energy gasto the secondary manifold, a low energy gas primary manifold outletcoupled to the primary manifold, a low energy gas secondary manifoldoutlet coupled to the secondary manifold, and a primary low energy gasstop and pressure control valve between the gas split and the low energygas primary manifold outlet; and a high energy gas delivery systemcomprising a high energy gas inlet and a high energy gas primarymanifold outlet coupled to the primary manifold; feeding the low energygas to the low energy gas inlet of the low energy gas delivery system;feeding the high energy gas to the high energy gas inlet of the highenergy gas delivery system; passing the first portion of the low energygas through the primary low energy gas stop and pressure control valve;feeding the first portion of the low energy gas to the primary manifoldfrom the low energy gas primary manifold outlet of the low energy gasdelivery system; feeding a second portion of the low energy gas to thesecondary manifold from the low energy gas secondary manifold outlet ofthe low energy gas delivery system; feeding the high energy gas to theprimary manifold from the high energy gas primary manifold outlet of thehigh energy gas delivery system; feeding the high energy gas and thefirst portion of the low energy gas to the turbine from the primarymanifold; and feeding the second portion of the low energy gas to theturbine from the secondary manifold, wherein the fuel delivery system isconfigured to allow the high energy gas to be delivered only to theprimary manifold.
 9. The method of claim 8, further comprising: passingthe first portion of the low energy gas through a primary low energy gascontrol valve after the step of passing the first portion of the lowenergy gas through the primary low energy gas stop and pressure controlvalve and before the step of feeding the first portion of the low energygas to the primary manifold; passing the second portion of the lowenergy gas through a secondary low energy gas control valve after thestep of feeding the low energy gas to the low energy gas delivery systemand before the step of feeding the second portion of the low energy gasto the secondary manifold; and passing the high energy gas through ahigh energy gas control valve after the step of feeding the high energygas to the high energy gas delivery system and before the step offeeding the high energy gas to the primary manifold.
 10. The method ofclaim 9, further comprising: passing the second portion of the lowenergy gas through a secondary low energy gas stop and pressure controlvalve after the step of feeding the low energy gas to the low energy gasdelivery system and before the step of passing the second portion of thelow energy gas through the secondary low energy gas control valve; andpassing the high energy gas through a high energy gas stop and pressurecontrol valve after the step of feeding the high energy gas to the highenergy gas delivery system and before the step of passing the highenergy gas through the high energy gas control valve.
 11. The method ofclaim 10, further comprising: passing the low energy gas through a lowenergy gas stop valve after the step of feeding the low energy gas tothe low energy gas delivery system and before the steps of passing thefirst portion of the low energy gas through the primary low energy gasstop and pressure control valve and passing the second portion of thelow energy gas through the secondary low energy gas stop and pressurecontrol valve; and passing the high energy gas through a high energy gasstop valve after the step of feeding the high energy gas to the highenergy gas delivery system and before the step of passing the highenergy gas through the high energy gas stop and pressure control valve.